3 a: a process by which information is exchanged between individuals through a common system of symbols, signs, or behavior <the function of pheromones in insect communication>; also : exchange of information b: personal rapport <a lack of communication between old and young persons>

4 plural a: a system (as of telephones) for communicating b: a system of routes for moving troops, supplies, and vehicles c: personnel engaged in communicating

5 plural but sing or plural in constr a: a technique for expressing ideas effectively (as in speech) b: the technology of the transmission of information (as by print or telecommunication)